Improvements in the hygroscopic properties of cotton cellulose by treatment with an endo-type cellulase from Streptomyces sp. KSM-26

The effect of enzymatic cellulolysis on the moisture-adsorbing properties of cotton cellulose was investigated, using a highly purified endo-type cellulase from Streptomyces sp. KSM-26. The time course of changes in the hygroscopicity of cotton reflected the time course of changes in the extent of the amorphous state of cotton, which was estimated from the amount of water that could bind to cotton, as determined by differential scanning calorimetry, during the hydrolytic process. The endo-type cellulase increased the degree of freedom of cellulose chains in the amorphous regions of cotton at the initial stage of the hydrolytic reaction, leading to major improvements in the moisture-adsorbing properties of cotton. The cellulase then caused the rapid decrease in the size of the amorphous regions with the release of reducing sugars as endo-cleavages in the amorphous regions increased, which reduced the hygroscopicity. The decrease in the hygroscopicity of cotton during enzymatic hydrolysis was followed by a second increase, as the cotton became more amorphous as a consequence of further hydrolysis of the crystalline regions of cotton. The effect of cellulase on the apparent degree of polymerization and the physical strength of cotton became detectable at the later stage of cellulolysis.     

Origin and control of high-temperature ferromagnetism in semiconductors

The extensive experimental and computational search for multifunctional materials has resulted in the development of semiconductor and oxide systems, such as (Ga,Mn)N, (Zn,Cr)Te and HfO(2), which exhibit surprisingly stable ferromagnetic signatures despite having a small or nominally zero concentration of magnetic elements. Here, we show that the ferromagnetism of (Zn,Cr)Te, and the associated magnetooptical and magnetotransport functionalities, are dominated by the formation of Cr-rich (Zn,Cr)Te metallic nanocrystals embedded in the Cr-poor (Zn,Cr)Te matrix. Importantly, the formation of these nanocrystals can be controlled by manipulating the charge state of the Cr ions during the epitaxy. The findings provide insight into the origin of ferromagnetism in a broad range of semiconductors and oxides, and indicate possible functionalities of these composite systems. Furthermore, they demonstrate a bottom-up method for self-organized nanostructure fabrication that is applicable to any system in which the charge state of a constituent depends on the Fermi-level position in the host semiconductor.     

Experimental and Thermodynamic Analysis on Phase Equilibria of Ni-rich Region in Ni-Al-Ti System

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Drilling of hard rocks by pulsed power

The drilling and demolition by low-duration, high-voltage electric pulses is based on the fact that, for very short times, the breakdown inside the solid dielectric occurs faster than the surface flashover benveen the electrodes. It was shown that most solid dielectrics could be broken down in insulating liquids, such as transformer oil, diesel fuel, and even in water. This study includes experimental and theoretical results on the drilling of rocks in insulating liquids, including transformer oil and diesel fuel     

Characteristics of Reaction Propagation in Combustion Synthesis of (Ti-B-C) Systems

Combustion syntheses of the (Ti-B-C) system have been investigated through measurements of its reaction heats and propagation rates. In order to clarify the reaction propagation characteristics, powder mixture compositions and the constituent carbon sizes were varied. As a result of the present work, it has been confirmed that the variation of the propagation rate related to the mixture ratios of the starting powders and greatly depended on carbon size. Three regimes categorize the present propagation characteristic: when the (Ti + 2B) component is predominant, the propagation rate decreases drastically with increasing the mole fraction of (Ti + C) component because the superiority of the reaction between Ti and B decreases. In the regime of the intermediate mole fraction, the propagation rate does not change as much. As the (Ti + C) component becomes predominant, the reaction between Ti and C overcomes the reaction with B and the propagation rate becomes large. In this regime, the large specific heat of boron might affect such a tendency.